1. Field of the Invention
The present invention relates to an image reproducing method, an image reproducing system using the method, and an image generating and reproducing method for providing a user that takes exercise with a series of images which can be varied according to user's movements when the user moves in a virtual reality environment which is created by the series of images and so on while he or she is using his or her body, for example, he or she walks, pedals a bicycle, does skating or roller-skating, or climbs a rocky mountain with both hands and both legs in the virtual reality environment.
2. Description of the Prior Art
Physical training machines such as indoor walking machines, and stationary bicycles, and apparatuses which can receive inputs through a joy stick or detect human being's movements to provide an artificial experience for the user exist in a form of making the user feel as if he or she is moving in a given artificial environment, which will be referred to as a virtual reality environment, by providing the user that is using such a machine with a series of images, which is one of elements that bring the realism into the user, according to user's movements. In order to provide a virtual reality environment for the user, natural scenes are captured and then converted into real-life images in advance. Thus such a machine or an apparatus can provide the user with a virtual reality environment by making appropriate changes to the on-screen image, which was converted from a natural scene captured using a video camera or the like, according to user's movements.
A prior art method of reproducing a series of images to generate a virtual reality environment includes the steps of converting each frame of each image which was converted from a natural scene captured using a video camera being moved at a low constant speed into a digital file, prestoring digital files in a medium such as a laser disc (LD), and reproducing digital files while thinning out some files according to user's movements. For example, reproducing every other digital file stored in the medium generates on-screen images which can be varied at a speed two times as fast as the original images were created. Reproducing every third digital file stored in the medium generates on-screen images which can be varied at a speed three times as fast as the original images were created.
While such the prior art method presents no problem as long as it reproduces a series of real-life image which was converted from natural scenes including a stationary object such as a building, a road, or a mountain captured using a video camera or the like according to a user's moving speed, it has a problem that, when reproducing a series of real-life images which was converted from natural scenes including a moving object such as the shaking of trees rustling in the wind, or a bird flying in the air, the user can sense that the speed of the shaking of trees or the flying speed of the bird is varied according to his or her movements, and this results in impairing the realism of the virtual reality environment. Furthermore, unnatural scene transitions between images displayed successively on the screen can cause the user to get motion sickness under certain circumstances depending on the user's moving speed.
Japanese Patent Application No. 313860 filed 1996, titled "Wellness System", and assigned to the assignee of the present invention discloses a step dynamic image reproducing method including the steps of storing a plurality of dynamic image cuts which were respectively shot or captured using an image generating device at rest such as a video camera placed at each of a plurality of shooting (or capturing) points which were arranged on a path in the real world along which the user will feel as if he or she moves in the virtual reality environment, and reproducing the series of dynamic image cuts while forwarding it cut by cut, to solve the above problem with the prior art method.
While the step dynamic image reproducing method disclosed in Japanese Patent Application No. 313860 solves the above problems that the realism of the virtual reality environment is impaired and the user gets motion sickness because of unnatural scene transitions between images displayed successively on the screen, the method has a disadvantage that the user cannot feel as if he or she is moving smoothly in the virtual reality environment because the plurality of shooting points are apart from each other and hence the continuity of the series of dynamic image cuts cannot be ensured, so that the user may feel as if he or she jumps between two adjacent shooting points each time he or she moves, for example, each time he or she takes a step when the user gets walking training.